i2c: rcar: protect against supurious interrupts on V3U

V3U creates spurious interrupts which we need to handle. This costs time
until BUS_PHASE_DATA can be activated which is problematic for Gen2 SoCs
and earlier. Because of this we introduce two interrupt handlers here
which will call a generic main irq function once the timing critical
stuff is done.

Signed-off-by: Wolfram Sang <wsa+renesas@sang-engineering.com>
Reviewed-by: Niklas Söderlund <niklas.soderlund+renesas@ragnatech.se>
Signed-off-by: Wolfram Sang <wsa@kernel.org>

diff --git a/drivers/i2c/busses/i2c-rcar.c b/drivers/i2c/busses/i2c-rcar.c
index 3c9c3a6..12f6d45 100644 (file)
--- a/drivers/i2c/busses/i2c-rcar.c
+++ b/drivers/i2c/busses/i2c-rcar.c
@@ -625,20 +625,11 @@ static bool rcar_i2c_slave_irq(struct rcar_i2c_priv *priv)
  * generated. It turned out that taking a spinlock at the beginning of the ISR
  * was already causing repeated messages. Thus, this driver was converted to
  * the now lockless behaviour. Please keep this in mind when hacking the driver.
+ * R-Car Gen3 seems to have this fixed but earlier versions than R-Car Gen2 are
+ * likely affected. Therefore, we have different interrupt handler entries.
  */
-static irqreturn_t rcar_i2c_irq(int irq, void *ptr)
+static irqreturn_t rcar_i2c_irq(int irq, struct rcar_i2c_priv *priv, u32 msr)
 {
-       struct rcar_i2c_priv *priv = ptr;
-       u32 msr;
-
-       /* Clear START or STOP immediately, except for REPSTART after read */
-       if (likely(!(priv->flags & ID_P_REP_AFTER_RD)))
-               rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_DATA);
-
-       msr = rcar_i2c_read(priv, ICMSR);
-
-       /* Only handle interrupts that are currently enabled */
-       msr &= rcar_i2c_read(priv, ICMIER);
        if (!msr) {
                if (rcar_i2c_slave_irq(priv))
                        return IRQ_HANDLED;
@@ -682,6 +673,41 @@ out:
        return IRQ_HANDLED;
 }
 
+static irqreturn_t rcar_i2c_gen2_irq(int irq, void *ptr)
+{
+       struct rcar_i2c_priv *priv = ptr;
+       u32 msr;
+
+       /* Clear START or STOP immediately, except for REPSTART after read */
+       if (likely(!(priv->flags & ID_P_REP_AFTER_RD)))
+               rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_DATA);
+
+       /* Only handle interrupts that are currently enabled */
+       msr = rcar_i2c_read(priv, ICMSR);
+       msr &= rcar_i2c_read(priv, ICMIER);
+
+       return rcar_i2c_irq(irq, priv, msr);
+}
+
+static irqreturn_t rcar_i2c_gen3_irq(int irq, void *ptr)
+{
+       struct rcar_i2c_priv *priv = ptr;
+       u32 msr;
+
+       /* Only handle interrupts that are currently enabled */
+       msr = rcar_i2c_read(priv, ICMSR);
+       msr &= rcar_i2c_read(priv, ICMIER);
+
+       /*
+        * Clear START or STOP immediately, except for REPSTART after read or
+        * if a spurious interrupt was detected.
+        */
+       if (likely(!(priv->flags & ID_P_REP_AFTER_RD) && msr))
+               rcar_i2c_write(priv, ICMCR, RCAR_BUS_PHASE_DATA);
+
+       return rcar_i2c_irq(irq, priv, msr);
+}
+
 static struct dma_chan *rcar_i2c_request_dma_chan(struct device *dev,
                                        enum dma_transfer_direction dir,
                                        dma_addr_t port_addr)
@@ -929,6 +955,7 @@ static int rcar_i2c_probe(struct platform_device *pdev)
        struct i2c_adapter *adap;
        struct device *dev = &pdev->dev;
        unsigned long irqflags = 0;
+       irqreturn_t (*irqhandler)(int irq, void *ptr) = rcar_i2c_gen3_irq;
        int ret;
 
        /* Otherwise logic will break because some bytes must always use PIO */
@@ -977,8 +1004,10 @@ static int rcar_i2c_probe(struct platform_device *pdev)
 
        rcar_i2c_write(priv, ICSAR, 0); /* Gen2: must be 0 if not using slave */
 
-       if (priv->devtype < I2C_RCAR_GEN3)
+       if (priv->devtype < I2C_RCAR_GEN3) {
                irqflags |= IRQF_NO_THREAD;
+               irqhandler = rcar_i2c_gen2_irq;
+       }
 
        if (priv->devtype == I2C_RCAR_GEN3) {
                priv->rstc = devm_reset_control_get_exclusive(&pdev->dev, NULL);
@@ -999,7 +1028,7 @@ static int rcar_i2c_probe(struct platform_device *pdev)
                priv->flags |= ID_P_HOST_NOTIFY;
 
        priv->irq = platform_get_irq(pdev, 0);
-       ret = devm_request_irq(dev, priv->irq, rcar_i2c_irq, irqflags, dev_name(dev), priv);
+       ret = devm_request_irq(dev, priv->irq, irqhandler, irqflags, dev_name(dev), priv);
        if (ret < 0) {
                dev_err(dev, "cannot get irq %d\n", priv->irq);
                goto out_pm_disable;